Alpha, beta, gammon
Nextcloud's declared strategy is to quickly grab some of the office space occupied by Microsoft & Google with lots of enhancements and apps. Hence move fast and break stuff is the cost of development. This has led to some friction with the crabby old SysAdmins looking for just a very stable federated database. Folks like me hang back two versions (currently 29.0.13) to minimise bugs and only move up when support ends.
With four weekly point updates and a version life of just 12 months - new bugs are a way of life, particularly new versions. The clue is the trailing 0 in 31.0.0. Only a very brave idiot would put that into production. Pre-evaluation more like. So it won't have live users. Doesn't mean it has no real data though.
Nextcloud Release Schedule